Sol-Gel Formation of Reticular Methyl-Silicate Materials by Hydrogen Peroxide Decomposition

A new method for the formation of reticular silicate and organically modified silicate is introduced. Monoliths were prepared by incorporating a few percent hydrogen peroxide in the sol-gel starting solution. For example, incorporation of 6-10% (v) hydrogen peroxide in base catalyzed sol-gel precursors of methyl-Ormosil yielded macroporous monoliths with a bi-modal pore size distribution. The average characteristic pore diameters were approximately 1.2 nm and 0.7 μm, depending on the sol-gel precursors used and the preparation protocol. The specific surface area was approximately 160 m²/g, contributed mainly by the microporous structure. A similar preparation procedure without hydrogen peroxide yielded only fractured or powdery materials. Presumably, the decomposition of the hydrogen peroxide yielded microbubbles, which formed templates for the polycondensation reaction. SEM, nitrogen adsorption isotherms and small angle X-ray spectroscopy were used to characterize the reticular materials.